This invention relates to an apatite whisker useful as a packed stationary phase employed in a column for column chromatography, a biotechnological material, such as a carrier for cell cultivation or isolation, or as a variety of fiber-reinforced composite materials or building materials as substitution materials for asbestos, and a method for preparation thereof.
As a method for preparing hydroxyapatite particles used as a biotechnological material, referred to hereinafter as HAp particles, there has hitherto proposed in, for example, Japanese Laid-open Patent Application No. 63-284 (1988), a method for preparing HAp fibers composed of HAp crystal aggregates, comprising uniformly dispersing HAp in an aqueous solution of a water-soluble high polymer, extruding the resulting liquid dispersion through a die composed of an array of spinneret nozzles, and molding and baking the extruded mass. There has also been proposed in Japanese Laid-open Patent Application No. 61-242968 (1986) a method for preparing HAp crystal particles as primary particles in the form of hexagonal prisms having an aspect ratio of 2.5 to 3.0 by carrying out hydrocuring reaction in an autoclave under pressure.
However, none of the HAp particles prepared by the above methods can be termed whiskers as far as their shape is concerned. These HAp particles are disadvantageous in that, if they are used as a carrier for cell cultivation, superior separating and spreading properties can not be developed, and that, if they are used as a fiber-reinforced composite material, the effect proper to the whiskers in improving the mechanical strength of the material can also not be produced.
On the other hand, silicon carbide and silicon nitride whiskers are used extensively industrially as reinforcing whiskers in a fiber-reinforced composite material, while asbestos is used extensively as a structural material for building or construction. However, these silicon carbide or nitride whiskers or asbestos presents serious problems with respect to hygienic safety because of the inherent chemical toxicity or cancerogenic properties due to the shape of the whiskers.